Medicine: Live Virus in the Jungle

Many experts are convinced that the best possible vaccine against
paralytic polio would be one containing live virus it is cheaper to
give, easier to take (by mouth) and should be more potent. But U.S.
health authorities are fearful that some virus might prove to be not
only live but virulent. They play it safe with the Salk vaccine, in
which the virus is killed with formaldehyde. Now, from darkest Africa,
comes the report of a trial in which a quarter-million people have been
given a live-virus vaccine made in the U.S. It appears...